n-dimensional matrix - Store the indexes of the n-th dimension in n-th cell

I have a n-dimensional matrix M. Now I'm looking for a way to create a 1xn cell array, where the index vector of the n-th dimension of M is stored in the n-th cell.

So for example: If the size of M were 40x30x50x20, the resulting cell array should look like this:

myCell = {[1:40], [1:30], [1:50], [1:20]};

How would I do this?

Answer 1

[fsgeek]

If M is explicitly defined then could you do

vect = size(M);            % vect = [40 30 50 20] in your example of M

                           %{
dim = length(vect);          So that we know how many cells there will be.
                             For your example dim == 4;
                           %} 
myCell = cell(1, dim);     % Pre-allocate for speed (thanks for reminding me, Jan!)    

for i = 1:dim
    myCell{i} = 1:vect(i); % assign a 1 x vect(i) array to each cell
end

The value of myCell after running this code is:

>> myCell

myCell = 

      [1x40 double]    [1x30 double]    [1x50 double]    [1x20 double]

I hope this helps!

Louis

[dave]

Perfect, thanks very much...

[Jan]

And for efficiency a pre-allocation is recommended:

myCell = cell(1, dim);